Rhapis chlorosis in full sun pool area

[Clem]

I maintain a number of large Rhapis excelsa in containers in pool lanais, pool decks and porches.  I have no issues with any of them except four plants located in large stoneware pots on a paved pool deck growing in full sunlight.  They’ve been in place for nearly a year and we’re doing well until we had two cold spells here in central Florida back in late December/early January.  Since then the existing foliage has become severely chlorotic (almost white) and the new foliage that is growing in now is doing the same.  They were fertilized with Sunniland palm fertilizer about two months ago and got one application of Peters 20-20-20 since then.  I suspect a pH issue but the plants are potted in the same medium (ProMix BX) as all the others that are doing great under the same regimen and conditions.  Thanks in advance for any wisdom you can impart.  I was a big fan of the late Dr. Henry Donselman and had even booked him as a speaker at a Mid-Atlantic Interior Landscape Conference many years ago.  I’m an experienced interiorscaper of over 43 years, recently relocated to Florida and enjoying the challenge of learning how to maintain tropical plants outdoors year-round.  Love this site!

[fotodimatti]

photos always help - even if it is just to attract attention to your problem

[PalmatierMeg]

Agree. Photos are a must.

I do suggest that you hold back on the Peters 20-20-20. It is too strong in nitrogen for palms and, I believe, is not time release. Palms are prone to root burn from quick release “blue granular” fertilizers unless to dilute them. Not worth the risk. I ended up using Sunniland blend for azaleas to fertilize our palms in Feb. because we could find - no - palm/shrub fertilizers at all. But the Sunniland azalea was very close to their palm blend and adequate.

[Clem]

Thanks for the replies so far.  I'll try to get a couple of photos this week.  

[Clem]

Here are some photos taken Tuesday.  New growth on some is coming in green but tends to fade to yellow and then almost white with brown necrotic burns on leaf tips and edges.  There’s a lot of tattered foliage due to wind exposure.  These are poolside outdoors but not close enough to get splashed with chlorinated pool water.  Thanks!